I Shall Avenge
by flavumetrubrum
Summary: Sequel to "I Shall Atone." A month after the Shredder's attack, Leo makes a promise to avenge everything he has done to his family. He determines to end the Shredder's evil reign, once and for all.
1. Chapter 1

Well, here' the first chapter of the sequel to "I Shall Atone." I know I didn't say anything last time, but for the sake of the story, assume that it takes place after the Fast Forward season. The Shredder has come back (I mean, duh—they didn't kill him so they might as well announce that he's coming back in the 2008 season) and the guys are back to fighting for their lives.

A big thanks to everyone who read my last story and especially to those who reviewed: 54Viruses, Merdeka21, BigfootSighted, Puldoh, Sapphire93, Lady-Of-The-Rings, Winged-Monkey, The Ghost of , aronoiiel, Michael J Angelo, Kyaserin Marii, villagemonster, Eridani23, hmw95, Diamond-Of-Longcleave, and LanceIsHot. I do not own the turtles or other related characters. Enjoy!

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Leo stood in the living are of their old lair, surveying the third home they had lost as a result of their endless fight with the Shredder. The lair was still standing, unlike their first two homes, and looked just as it had the day Saki himself had entered their home and attacked them. They had moved all of their things into their new lair leaving this one looking much as it had when they had moved in.

It seemed like so much had changed in the month since the attack. Leo still couldn't move his right hand, and although he was able to use his left hand he was having a hard time accepting the fact that he might never use two katanas again. The turtles and Master Splinter were still trying to adjust to a new home. The Shredder had been keeping a low profile, and Leo was nervous that meant he was planning something big. They had lost too much already; he didn't want to have to defeat the Shredder again.

Leo had thought that after Ch'rell had been banished they had gotten rid of him for good. But, not for the first time, he had been wrong. The Shredder had returned and they whole process had started over again. Leo sighed and rubbed his left hand over the scars on his plastron. They weren't the first he had received from his fights with the Shredder, and they probably wouldn't be the last. The Shredder had taken too much from him and his family, and Leo was determined to end the cycle for good this time.

"You can count on it, Shredder," he said into the heavy silence. "I shall end this—I shall avenge!"

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So there's the prologue. I hope you enjoyed it. I'm thinking there's going to be more action in this story than in "I Shall Atone," but there'll be as much if not more focus on the guys' emotions too. Thanks for reading—I'll update as soon as I can.


	2. Chapter 2

Thanks so much to Eridani23, winged-monkey, 54Viruses, Puldoh, Sapphire93, LanceIsHot, hmw95, BigfootSighted, Kyaserin Marii, and Michael J Angelo for your reviews. I still don't own the turtles or other related characters. Enjoy!

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Mikey stood at the door to the dojo, watching Leo as he went through yet another strenuous set of katas. He held only one sword, in his left hand, but his right hand flowed through the movements as if it were actually holding a weapon. Sweat beaded on Leo's forehead and slid down the side of him face, leaving glistening trails. His chest rose and fell with slightly accelerated breathing.

Mikey's eyes wandered as of their own accord to stare at the large scars marking his plastron. The three pale grooves began just below the upper lip and traveled in a crooked trail all the way to the stomach, becoming wider and more pronounced the lower they got. Mikey shuddered and tore his eyes away, trying to push the image of Leo's blood pulsing out of his stomach as he lay on the floor at his feet out of his mind. He had dealt with his feelings of guilt, with the help of Leo and Master Splinter, but the images still haunted him.

As Leo turned his back to the door and began a new kata, Mikey thought of all the other scars his brother had accumulated through the years. True, they all had scars from their many battles against the Shredder, but it seemed that Leo always got the worst of it. He still had various smaller scars littering his body from the time he was ambushed by the Foot and beaten within an inch of his life, and the huge chunk missing from his shell was a painful reminder of what had happened on the Shredder's space ship. Mikey didn't know what it was about Leo, but he seemed to be a magnet for near-death experiences.

Mikey took a deep breath and walked away from the dojo. He longed to run inside and drag Leo away, to make him give it a rest, but he knew the effort would be fruitless. So, instead of watching his oldest brother work himself almost to the point of collapse, he bounded off to play video games, plastering his trademark "Mikey" expression on his face.

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Raph stumbled down the stairs five minutes before practice to see Mikey already playing video games, and Master Splinter drinking his tea at the kitchen table. He heard Don moving around in his lab and the sound of Leo warming up in the dojo. He sighed when he heard the ever-present and yet eerily unfamiliar noises coming from the room. He didn't think he would ever get used to hearing only one katana slice through the air as Leo did his katas. It was just unnatural.

Mikey bounded past him on his way to the dojo, calling to him as he did, "Come on, dude, it's time for practice!" Raph shook his head and mumbled that he was on his way, wondering where Mikey got his endless supply of energy. Don joined him and the two walked into the dojo to warm up, followed closely by Master Splinter.

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The first thing Don noticed upon entering the dojo was that Leo already looked as if he had completed a full practice and then immediately gone for a run through the sewers. His forehead and neck shone with sweat and his chest was heaving slightly. Don frowned but thought better of saying anything. Maybe Leo would rest after practice…. But Donny knew it was too much to hope for. It had been all any of them could do to keep Leo from practicing long enough for the cuts on his plastron to heal over, and the time off had been hard on the perfectionistic turtle. As soon as (and probably sooner, for all Donny knew) Leo had been pronounced physically able, he had taken to getting himself back in shape with a vengeance. A week later he was still working himself to exhaustion. Don knew that after a month of down-time it was unhealthy, but he also knew that suggesting anything of the sort to Leo was unhealthy. So he kept his mouth shut and began to warm up next to his brothers.

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Okay, so this is kind of another set-up chapter in which nothing to speak of happens, but I think it's kind of important to the story to show Leo's drive. Don't worry, he's not going to go all emo and funky like he did after the exodus, but he is determined to keep his promise to defeat the Shredder for good, and to do so he thinks he has to be perfect. By the way, I know I mentioned more action in this story, but that may not come until later. Stuff will happen, but the exciting action will come closer to the climax and end than to the beginning. So hang in there, I promise it will get better. Thanks so much for reading!


	3. Chapter 3

Thanks so much to Eridani23, winged-monkey, 54Viruses, Puldoh, Sapphire93, LanceIsHot, hmw95, BigfootSighted, Kyaserin Marii, and Michael J Angelo for your reviews. I still don't own the turtles or other related characters. Enjoy!

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After practice Leo stayed behind in the dojo to meditate. He knelt into the lotus position and placed his hands on his knees, closing his eyes and taking deep breaths. Normally he could enter the meditative state almost instantaneously, but he had a lot on his mind and he found it hard to clear his thoughts. After five minutes of trying to calm himself he sighed and opened his eyes. He stared down at his hands and let the images he had been trying so hard to banish flood his mind.

Leo clenched his left hand into a fist, wincing as the sore muscles flexed. He looked at his right hand, still wrapped in bandages, and tried to do the same. He was rewarded with a slight twitching of his left finger—the only thing he had been able to accomplish in all the "therapy sessions" Donny had made him take. He should have been grateful for his brother's concern, but he didn't really see the point. There was little or no chance the tendons would heal together enough to work, and Leo didn't see the point in hoping for that chance. So he had resigned himself to simply doing the best he could with one katana.

At first it had been a nightmare. He had reached the point in his training where he no longer had to think about what he did as he fought. It came naturally. And he had bruises to prove it. The first time he sparred with one of his brothers, he had reverted to his old habits. An attempt to block Donny's bo staff with his right katana ended up with the staff finding its mark—hard—on his shoulder. Donny had been horrified, but Leo blamed himself entirely. He began to practice with his right hand tucked inside his belt, relying solely on his one hand and katana. As soon he got used to only attacking and blocking with one sword, he began to practice using his right arm as a weapon. He couldn't make a fist, but he could still use his arm to block and even occasionally get in a hit.

Leo pushed himself up from the floor, abandoning all hope of meditating. He walked slowly out of the dojo, making his way over to the couch where Mikey was sitting staring at the TV. He lowered himself onto the cushion next to his little brother and glanced at the cartoon that was showing.

"Leo! I thought you were meditating," Mikey said when he realized who was sitting next to him.

"Um, I decided to take a break," Leo said, not wanting to admit he couldn't clear his mind.

"Really?" Leo's heart sank at the joyful, hopeful look on his baby brother's face. Had he really been that bad lately? _Yeah, I guess I have,_ he thought.

"Yeah, but I can go back if you want me to," Leo smiled. Mikey's eyes widened even more, if that was possible, and he grabbed Leo's wrist.

"No, you can stay. I didn't mean…."

"Relax, Mikey, I was just kidding." Leo felt guilt building in the pit of his stomach. He hadn't known he had been hurting his brother by practicing so hard. He hadn't wanted to do anything of the sort—in fact, he was working so hard so that his little brothers _wouldn't _get hurt. Maybe he should lay off a little….

"Oh. So do you wanna play video games or something? I just beat my high score on…."

"Sure, Mikey," Leo interrupted before Mikey could begin one of his infamous monologues. "Whatever you want to play." Mikey beamed and leaped over the coffee table, landing in front of his game system. Leo smiled as Mikey began to chatter happily about one game or another as he rifled through his extensive collection. "Just pick one, Mikey."

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That night Leo lay awake in bed thinking about the look on Mikey's face and the way he had seemed so happy with such a small thing. He kicked his blanket off and flopped over onto his stomach, trying to push away the guilty feeling. He had only been trying to protect his brothers, and he ended up making them worry. Couldn't he do anything right? He had been trying to get rid of what was hurting them, and he had become something that was hurting them. Leo got out of bed and began to pace back and forth on his floor. He knew he had to train to become proficient enough with only one katana to defeat 

the Shredder, but he didn't want to overdo it if that meant he was hurting his family. Maybe if he trained alone, at night…. Leo picked up his katana sheaths from their stand by his bed and pulled them over his shoulder. He pulled out his left sword and began to go through one of his katas. Yes, he would train in secret so that his brothers wouldn't have to worry.

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Sorry it took me a little while to get this chapter out. I wanted to work on my ideas for my one-shots and this kind of got put on hold for a day. I hope you enjoyed this chapter. More set-up… yay! Thanks for reading!


	4. Chapter 4

Thanks so much to Eridani23, winged-monkey, 54Viruses, Puldoh, Sapphire93, LanceIsHot, hmw95, BigfootSighted, Kyaserin Marii, Michael J Angelo, and The Ghost of for your reviews. I still don't own the turtles or other related characters. Enjoy!

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Leo was up and ready for practice with his brothers at the normal time the next morning. He had slept for a couple hours before getting up and heading to the dojo to warm up, and he felt plenty rested to attend practice. Not that he wouldn't have if he didn't….

Leo stretched his stiff muscles and drew his left-hand katana, moving through the familiar steps of a simple kata. Now, where normally he would have blocked an imaginary weapon with his right sword, he used his arm to deflect the attack. He knew he wasn't up to his normal standards yet—in endurance or in ninjitsu—but he was determined to meet and even surpass his previous ability. His brothers soon joined him and the four turtles warmed up side-by-side.

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Mikey moved through the katas Master Splinter called out, trying to focus on what he was doing. He kept stealing glances at Leo, however, who seemed to be tiring a little bit. He was almost completely back in shape after his injury, but for some reason he appeared to still be lethargic. Mikey didn't know as much about such things as Don, but he was good at reading his older brothers; Leo was still working too hard. Mikey had no idea what was causing his oldest brother's exhaustion, but whatever it was he wanted it to stop.

Leo hadn't really been himself since the attack on the old lair. True, he had been a lot better than after the incident with Karai on the Shredder's space ship, but he had seemed too focused, too determined—even for Leo. Something was bothering him….

"And, finish!" Master Splinter said, tapping his walking stick on the ground. The four brothers stopped and bowed before walking in different directions to catch their breaths. Mikey wiped the sweat off his face with a towel, then took a long drink from his water bottle. "You will now spar—Raphael against Donatello and Leonardo against Michelangelo."

Mikey had noticed that their sensei had been pairing Leo with him and Don ever since Leo had started practicing with them again. He guessed it was because Leo wasn't quite up to par yet and he didn't want Raph accidently hurting him. He and Leo moved to one side of the dojo while Don and Raph took the other. Leo attacked first with a flying kick, which Mikey easily dodged.

The two always started matches like this—feeling each other out, using simple attacks to judge the other's strength. But as the fight progressed Leo's attacks didn't become any stronger. His aim was off and his blocks were slow. Mikey saw his opportunity to actually beat Leo for once and began to fight harder, careful not to hurt his brother.

Mikey swung his left 'chuck at Leo's right side, hoping to cause Leo to have to block with his left sword. He immediately aimed a blow for Leo's left shoulder, which he expected to be left unprotected. Instead, Leo's sword blocked the nun chuck aimed for his shoulder and he brought his right arm to meet the other weapon. The wood of Mikey's nun chuck connected with the flesh on Leo's arm with a loud thud, causing Mikey to shudder. Leo grunted and moved back into a defensive stance.

Mikey immediately shoved his 'chucks into his belt, staring at the ugly bruise already forming on Leo's green skin. "Dude, I am so sorry."

Leo merely shook his head and nodded to Mikey's weapons, indicating he wanted to continue the fight. The younger turtle crossed his arms and said stubbornly, "No way. You're hurt."

"Mikey, it's nothing. I did that on purpose; now come on."

"You what?" Mikey shouted, looking at Leo's arm. By this time, the other three mutants in the room had gathered around, eyeing the bruise and staring at Leo oddly.

"The arm's not good for much else; I can use it to block. It's no big deal," Leo protested, still holding his swords in his hand. Don stepped forward and grabbed Leo's right arm, examining the bruise.

"If you're going to use it to block you need to protect is somehow. What if that had been Raph's sai? Or a Foot ninja with a katana? You can't just use unprotected flesh to block serious attacks."

"Donny…."

"Don't 'Donny' me. You can block with it all you want if you let me make something to protect it." Leo sighed resignedly, but he was obviously frustrated.

"Fine. But make it quick; I want to finish this match."

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Leo stood in his bedroom, examining the shiny metal armor Don had made to cover his forearm. It covered the top of his arm, spreading from the back of his hand up to the elbow, and was strapped on underneath. He had finished sparring with it and it had helped a lot. He had even tried it out with one of his katana—not a scratch. He had to admit that he was grateful to Donny for insisting on making it for him. His bruise from earlier was still aching.

Leo moved to draw his left katana, prepared to practice all night again. He glanced at the clock and saw that it read midnight. _I'll just stay up until two. I need more sleep tonight,_ he promised himself, beginning a kata. He soon lost track of time, however, and continued to practice all through the night.

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A big thanks to BigfootSighted for the idea of the armor! So very cool! There's going to be a fight next chapter… I know, I know… it's about time, right? I'm not going to say with who but hopefully it will be exciting. Thanks so much for reading faithfully.


	5. Chapter 5

Thanks so much to Eridani23, winged-monkey, 54Viruses, Puldoh, Sapphire93, LanceIsHot, hmw95, BigfootSighted, Kyaserin Marii, Michael J Angelo, The Ghost of , maryshine, and KittyGrl24 for your reviews. I still don't own the turtles or other related characters. Enjoy!

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Leo breathed in the fresh air, relieved to finally be out of the sewers. He hadn't been allowed topside since the Shredder's attack, and he had been starting to get stir-crazy. Don and Master Splinter had agreed he could accompany his brothers on a training run, however, and Leo was relishing in the freedom.

"Yo Leo, ya comin'?" Raph called from the next roof over. Leo opened his eyes, seeing his brothers had stopped also and were staring back at him.

"Yeah, I was just enjoying the air," he called back, hurrying after the others. He flipped easily over the gap between the roof tops and landed a few feet from where they were standing. "It's been too long."

"I thought _I _was the one who couldn't stand bein' cooped up for a little while," Raph sneered good-naturedly.

"A little while I can take," Leo laughed, looking pointedly at Don. "But six weeks is a little extreme."

The brainy turtle grinned sheepishly, holding up his hands. "Fine, next time I'll let you go running around before you're ready. I'll just have you know I had Sensei's support the whole time."

"Like either of you could stop him if you wanted to," Mikey joked, joining in the brotherly banter. Leo smiled contentedly. Things had been good among the turtles since he had stopped practicing so hard during the day. He may not have been getting enough sleep, but it was worth it.

Raph snorted and took off across the rooftop, calling over his shoulder, "I thought you were tired of just sitting around yackin', Fearless Leader. I came out here to run." The other three turtles were soon at his side, again running and leaping from roof to roof.

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Karai stood on a roof top watching the turtles as they ran across New York. "It has been a long time, Leonardo. I am looking forward to defeating you yet again. Foot ninjas, attack!"

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Mikey ran excitedly beside his brothers, enjoying the time together. This was what he had missed after the Shredder came into their lives; the care-free training and running, spending time together as a family and not as a miniature army. He glanced at Leo. His oldest brother had been great to hang out with lately, but he seemed tired. It was almost as if he was being run down by his lack of training.

As Mikey watched his brother, Leo suddenly stopped and whirled around, drawing his sword. The other three turtles immediately followed suit, coming face-to-face with a horde of Foot ninja. "Is one training run without an ambush too much to ask for? You guys are really starting to bug me," Raph huffed, exasperation written plainly on his face. Don seemed immensely disappointed, and Mikey was indignant that their perfect night had been ruined by the intrusion. But Leo was harder to read. His content expression was gone and he now wore a mask of determination and focus.

"And you four have been 'bugging' me for some time now, turtles," a chillingly familiar voice said. Mikey watched in horror as the slim figure of Karai walked out from among the ninjas, swords drawn and at the ready. "But you shall be a sword in my side and the side of my father no longer. I have come to end this, once and for all." Mikey swallowed, staring at the woman who had caused their family so much pain. She had stayed away for so long, he had almost forgotten about her; but now here she was, so shortly after the return of her father, threatening their lives one again.

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As Leo stared at Karai, he felt all the anger and resentment and disappointment she had caused him come flooding back, breaking the dam he had built to hide them. He rushed forward, his sword clanging loudly with both of hers, as the Foot ninjas raced to attack his brothers. He glared at her, allowing all the hate he felt toward her to fill his eyes. She glared back, and the two stood that way for some time, standing in the middle of the battle. Suddenly Karai broke away and circled around him, a haughty expression covering her face.

"I did not come to make faces at you, Leonardo. I came to finally destroy you and your worthless family and fulfill my destiny."

"There was a time when you believed your destiny was something greater than simply following orders and being your father's assassin," Leo spat back, wincing at how bitter his voice sounded. A second later their blades were locked again. Karai's warm breath brushed across his cheek, and her fiery eyes bored into his.

"I am not merely my father's assassin, Leonardo. I am here because I wish to destroy you." She kicked at his chest, and he sidestepped the blow, knocking her leg out of the way with his armored arm. It knocked him off balance, however, and he stumbled slightly before regaining his footing.

_Something's wrong, _he thought. _I shouldn't have even had to block that. _Leo jumped at Karai, using his one katana to attack while trying to draw her attention away from his other arm. If he could distract her enough with one hand he could use the armor to gain an advantage. Or at least level the playing field.

Leo was breathing hard by the time he saw his opening. He knocked her blades to the side with his own and swung his other arm at her ribs. He cringed at the sickening feeling of bones shifting under his hand and the sound of the ribs cracking. Karai cried out and fell to her knees, holding her stomach. Leo backed up, knowing he should do something to effectively end the fight but suddenly feeling dizzy and fatigued. Karai looked up, her face contorted with pain, and threw one of her swords at him. He stumbled backward quickly, trying to avoid the blade, and his heels collided with the lip of the roof. His body continued backward and he fell.

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Under normal circumstances I would be nice and not end it here, but my mom says I actually have to do school (what's the point of being homeschooled, anyway?) so I'm not able to update as often as I would like to. Therefore, I wanted to get this up while I could to give you guys a little something to go on. Well, that and I'm in an incredibly cruel mood… haha. I promise to update as soon as I can, and to avoid cliffhangers as much as possible in future chapters. Thanks so much for reading and supporting me even in my most evil of moments.


	6. Chapter 6

Thanks so much to Eridani23, winged-monkey, 54Viruses, Puldoh, Sapphire93, LanceIsHot, hmw95, BigfootSighted, Kyaserin Marii, Michael J Angelo, The Ghost of , maryshine, KittyGrl24, and Koriat Cyredanthem for your reviews. I still don't own the turtles or other related characters. Enjoy!

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Leo grabbed for the wall as the weight of his shell carried him backward off of the building. He only managed to brush the ledge, however, and he continued to fall toward the alley below. He slammed into the fire escape, slightly slowing his descent, before landing hard on his plastron in the middle of the alley. He tried to push himself up but fell back to the ground. He was so tired… all he wanted to do was sleep. Leo forced himself to climb slowly to his feet, feeling every bone in his body protest the movement. He pulled himself up the fire escape, half crawling, half dragging himself. He had to help his brothers…. Karai was still up there….

Leo eventually reached the top of the fire escape but didn't hear any sounds of fighting coming from the roof. He pulled himself over the ledge, almost crying out as his sore plastron scraped across the bricks, and landed on the other side, barely managing to stay on his feet. He was met with the stunned stares of his three younger brothers.

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Don stared at his oldest brother, surprised to see him standing. The building wasn't a tall one, but a free fall like that could kill someone, or at least hurt them badly enough that they couldn't climb a fire escape. Don recovered, however, when Mikey cried out, "Leo! You're okay!" The brainy turtle ran to Leo's side, supporting him and instinctively checking him for any injuries.

He had a cut over his left eye, but it didn't worry Don too much. He didn't seem to have a concussion, and Don couldn't find any broken bones. He stepped back and stared at his brother, who was now leaning heavily against Mikey. "Well, you seem to be okay. Bruised, but fine."

Raph snorted. "Only Leo could manage to fall off of a building without breaking anything," he muttered. Suddenly Leo's eyes rolled back into his head and his knees gave out. The only thing that kept him from hitting the roof was the arm he had around Mikey's shoulders.

"Leo!" Mikey shouted, lowering his unconscious brother to the ground. "Donny, what's wrong?" Raph's eye ridges were furrowed, betraying the worry he refused to voice. After checking him over once again, Don stood up and hoisted Leo to his feet, pulling his free arm over his shoulders.

"He's completely exhausted and between that and the fall, his body needed to shut down for a while. He'll be fine; he's basically just sleeping," Don explained. He looked concerned, however, and glanced at Raph pointedly. Raph nodded, turning his gaze to Leo. Something was up, and he was determined to find out what it was.

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Leo awoke in Donny's lab, lying on his shell on a cot. The room was dark and seemed to be otherwise unoccupied. Leo pushed himself up, his muscles protesting the cautious movement. He groaned and wrapped an arm across his plastron, holding his bruised ribs. His head pounded and his torso throbbed, and he felt completely drained. He glanced around, wondering if he should try to go to his room or just stay there. He had just decided to lay back down when a voice interrupted the heavy silence.

"So how long were you planning on going without sleeping?" Donny asked. Leo cringed at the blunt question, berating himself for being so careless.

"I slept every night, Don," Leo answered, refusing to look at his brother's face.

"Don't give me that, Leo. A couple hours don't count. You could have gotten yourself killed. You fell off a _building_, Leo. You're lucky Karai didn't impale you when she had the chance. Heck, you're lucky _Raph_ hasn't killed you yet."

"Don, I have to train…."

"It's always about training, Leo. What good did all that training do when Karai pushed you off the roof, huh? Look, we all thought you were laying off when you quit training like a madman during the day. Imagine how Mikey would feel if he found out you were just waiting until we were all asleep. Do you think that would help the situation?" Don stopped and sighed. "Look, Leo. We're worried about you. If you keep doing this to yourself, next time you could get killed."

Leo lost all will to argue when Don finished speaking. There he went again, worrying his brothers and making them suffer. He stared hard at the floor, cursing his weakness. "I'm sorry, Donny," he whispered, trying to keep the thick guilt out of his voice. He obviously failed, however, because the next thing he knew Don was keeling in front of him, staring sternly at his face.

"Don't beat yourself up about this, Leonardo. We appreciate what you're trying to do, but just think about it this way. If you train too hard, you might get killed. If you get killed, there will be nothing you can do to help us. Training is all well and good, but in measured doses." Don put his hand on Leo's shoulder and gently pushed him back onto his shell. "Get some sleep. And from now on, don't work yourself so hard. If Karai comes back for revenge—and you can pretty safely bet she will—we'll need to be ready. _All_ of us."

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I'm sorry it's short and took me so long to post, but life caught up to me. I should have more time to write soon, however, and hopefully it won't be such a long wait again. Thanks for reading faithfully.


	7. Chapter 7

I really have to apologize profusely for how lazy I've been with the updates lately. I wish I had some super-cool excuse that would make it okay, but unfortunately I don't. It really is my fault, and I'm really sorry. Thank you so much for being patient with me.

Also, thanks so much to Eridani23, winged-monkey, 54Viruses, Puldoh, Sapphire93, LanceIsHot, hmw95, BigfootSighted, Kyaserin Marii, Michael J Angelo, The Ghost of FF. Net, maryshine, KittyGrl24, and Koriat Cyredanthem for your reviews. I still don't own the turtles or other related characters. Enjoy!

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Raph watched Leo as the older turtle stood in the center of the dojo, facing off against an invisible opponent. Leo circled a few times before attacking his "foe" with a few well-practiced moves. He flowed through the steps with fluid ease, blocking and attacking in turn.

Raph was amazed by how little Leo's fighting skills had been affected by, for all practical purposes, the loss of his right hand. At first it had seemed so weird to only hear one blade slicing through the air, or to see Leo blocking with his arm as if it were a weapon in and of itself. But with time, it had become almost… normal. As much as Raph hated to admit it, Leo could still kick his butt in the dojo any day of the week. It was almost as if the incident had made him stronger instead of taking something away from him.

Ever since their encounter with Karai the month before, things had been very quiet. There was no Foot activity and very little Purple Dragon action. Even Leo was less… intense. Raph assumed that whatever Don had said to him in his lab had actually gotten through to their Fearless Leader for once. Raph himself had been about ready to literally beat some sense into his older brother, but luckily Donny had insisted on talking to him alone. Because it looked like it had worked. Raph hadn't quite hung up his boxing gloves yet, but for now he was content to wait and watch… for once.

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"Dinner's ready!" Mikey's cry carried through the whole lair, practically daring his family to ignore him. _That's probably how Saki found the old lair_, Don thought wryly, leaving his lab and heading into the kitchen. He met Raph on the way and the two brothers sat down at the table across from each other, sharing a friendly nod. Leo was only thirty seconds behind, wiping a thin layer of sweat from his face with a towel. As soon as Master Splinter joined them, Mikey set the frozen pizzas on the table and took his seat next to Raph, across from Leo.

Don had to admit, he was proud of his oldest brother. He had expected him to take it easy for a day or two at most, but so far Leo had been reasonable in the time he spent training. He was getting plenty of sleep, probably for the first time in years, and he seemed to be growing steadily stronger. Master Splinter had seemed pleased with his progress as well, and Don couldn't help but wonder if that was at least part of the reason Leo was keeping it up. But maybe the blue-banded turtle actually understood what Don had said. Maybe.

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As soon as dinner was done the brothers moved into the living area. Mikey flipped the TV on as if by instinct and flopped down on the couch, flipping through the channels. Raph continued on into the dojo to get a workout, and Don sat down in an armchair with a book. Leo almost followed Raph into the other room but hesitated at the door. He looked back over his shoulder before joining Mikey on the couch.

"Wanna watch a movie or… something?" Leo asked, wincing at how stupid the question sounded. Mikey looked up from the TV and his eyes lit up.

"Sure, bro. Whaddya wanna watch?"

"Um…." Leo was vaguely aware of Don watching him over his book, but chose to ignore this. "I don't know. Whatever you want." Mikey's grin nearly split his face in half as he leaped off the couch and deliberately pulled a DVD case out of their entertainment center.

"Napoleon Dynamite it is, then!" Donny groaned and Leo instantly regretted his choice of words. Mikey, however, ignored his brothers' reactions and inserted the disc into their DVD player. He ran into the kitchen, yelling something about popcorn.

"Remind me to be a little more specific next time, huh Donny?" Leo groaned, turning to face his younger brother.

"I'm surprised you didn't know any better. _Never_ give Mikey free reign to choose any form of entertainment. Especially after Casey brings over a bag of the top ten worst movies ever made."

"I'll remember this time, you can count on it."

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Mikey kept shooting his oldest brother glances as they watched the movie. He wasn't the most observant turtle in the world, but he had noticed a change in his brother ever since their fight with Karai. He seemed… happier. He wasn't as tired or cranky, and he spent less time training. Mikey couldn't be happier; it meant someone to hang out with who didn't over-analyze everything or torment him just for the heck of it.

Leo hadn't been this much fun since before they met the Shredder for the first time. It seemed like forever ago, but in reality it was only a year and a half. So much had happened during that time, and Mikey was glad to finally have his big brother back. Hopefully he stayed this time….

As the movie ended the three turtles in the living area stood up and headed upstairs. Raph followed close behind, and the family dispersed into their rooms for the night. Mikey lingered outside Leo's door for a while before entering his and closing the door. He smiled as he fell asleep, satisfied by what he had seen. Leo had immediately fallen asleep, meaning he wasn't training during the night.

Maybe Leo would stay this time….

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Again, I am so sorry for the wait. I'll try to do better. I hope you enjoyed this chapter. I'll have more out as soon as I can.

Oh, and by the way, I don't like Napoleon Dynamite, but I thought it sounded like something Mikey would like. I hope I didn't offend anyone with Donny's and Leo's comments.


	8. Chapter 8

Um…. Hi! I have to apologize for the insane seven month break in updating this story. I still have several others I'm working on, but I've decided to go back and finish some of them before I do any more. I read all of the chapters I have posted for this story so far, and I'm going to work on this one first. Thanks so much to anyone who's stuck with me this long.

Without further ado, the long overdue continuation of "I Shall Avenge"

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Leo stood on the rooftop overlooking the city of New York. His brothers were somewhere to his left on another rooftop; he could hear their friendly bickering as clearly as if they were right next to him. He knew he should tell them to keep it down, but he couldn't find it in himself to be annoyed. On the contrary, he enjoyed hearing them getting along so well. He was more inclined to join in himself than to put a damper on their day out.

This was the first time they had ventured topside since Karai's attack, and so far there hadn't been any sign of the Foot. Technically they were supposed to be patrolling the city, searching for any indication as to what the woman's plans were, but none of them were really in the mood to go looking for trouble. Not even Raph. So instead they had gone for a quick run before settling onto the rooftops for an evening of relaxation. It wasn't often that they got to spend down time outside of the sewers.

Still, Leo couldn't help but excuse himself from the impromptu wrestling match and leap to the neighboring rooftop. He cast his eyes over the surrounding area, his seemingly inborn leader instincts kicking in. He just had to be sure that they were alone. Then he could rejoin his brothers and really relax.

He was finally satisfied and had turned to head back to the other rooftop when an arrow embedded itself in the gravel at his feet. He whirled around, quickly drawing his katana from its sheath, and scanned his surroundings for any sign of an enemy. Not finding any he glanced back at the arrow. It was wrapped in a piece of paper that bore the Foot insignia, and Leo frowned. This was how the Shredder had first made contact with him and his family. He glanced toward his brothers and was relieved to discover that they hadn't noticed. He quickly unrolled the paper and tossed the arrow aside.

_ Leonardo, I wish to meet with you in private. There are some things we must discuss that are of great consequence both to the Foot clan and to your family. Come alone; there is no reason to involve your brothers in our dispute._

_ Oroku Karai_

Beneath the note Karai had listed the desired time and place for their meeting. Leo folded the paper and tucked it into his belt, unsure what to think about the message. He rubbed his forehead and sighed in frustration. Why did everything have to get so complicated right when it was going so well?

"Leo, help! Raph's trying to murder me!" Mikey's voice carried easily over the distance between them and Leo quickly pushed the events of the last few moments to the back of his mind. He would think about that later. He quickly made his way back to his brothers and laughed at the scene before him.

Mikey was sprawled on his plastron on the rooftop, trying desperately to wriggle his way out from under a very clearly aggravated Raph. Don stood off to the side, holding his stomach and shaking with laughter. After weighing his options, Leo decided to join his brainy brother and watch as the scene played out. As Mikey screamed for assistance, Leo all but forgot about the mysterious and cryptic message.

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Well, I know that wasn't very long or anything, but I hope it wasn't too disappointing. I should be posting again soon. Again, I'm sorry for the insane wait. Thanks again to anyone who actually read this.


	9. Chapter 9

Thanks to everyone who reviewed the last chapter. This one is short, too, and I'm sorry. Hopefully it will pick up soon. Enjoy!

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Right after midnight Leo crept out of his room, holding his breath and listening for any signs that he wasn't the only one awake. He quickly made his way to the edge of their upper level and flipped down to the living area. With one more glance behind him, he slipped out of the lair and down the sewer tunnel.

Fifteen minutes later he was at the address specified by Karai. It was an old abandoned warehouse, and Leo didn't see any sings of either his enemy or civilians. He stayed outside the large double doors, not wanting to venture into a possible ambush. He hoped that Karai would keep her word, but the more he saw of her the more he doubted that she was any different than her father.

At 12:20, the appointed time, Karai dropped to a crouch in front of him. Leo glanced around quickly but didn't see that she had brought anyone with her. "I am alone, Leonardo. As I hope you are, as well." At Leo's icy glare she nodded quickly. "Of course. I knew you would act honorably."

"What is this about, Karai? I would really rather be at home sleeping right now," Leo said, not even trying to disguise the hostility in his voice.

"As would I, Leonardo. But this is the only way we could meet without my father's knowledge," the woman replied.

Leo snorted. "How do I know the Shredder didn't set this up and send you to convince me we're alone? For all I know the whole Foot army could be inside this warehouse just waiting for orders to attack."

"I would not set you up in such a way. As much as I hate you I do not wish to see you destroyed so dishonorably."

"Touching," Leo sneered. This woman was really beginning to get under his shell.

"You must trust me, Leonardo."

"Trust you?" Leo asked disbelievingly. He barely stopped himself from wincing at how bitter he sounded. "Why on earth should I trust you? I've given you plenty of chances before, and you betrayed me and my family every time. I have no reason to trust you."

Karai sighed in exasperation. "You wouldn't have come if you truly suspected treachery." She paused for a moment and seemed to collect herself. "The reason I asked to meet with you is to issue a challenge. We both wish to defeat each other; that much is obvious. But as I said in my letter, I see no need to involve either your family or the Foot clan in our dispute. Therefore, I challenge you to a one-on-one duel to the death."

Leo was struck speechless for a moment. This wasn't exactly what he had been expecting. "Oh? And you attacked my whole family the other day because…?" he let his question trail off.

"I was acting on my father's orders. He wishes to destroy your brothers and father as well."

"Then what will a duel accomplish? No matter the outcome, the Foot will just keep attacking my family."

"If you kill me, there will be one less enemy for you to worry about. If I defeat you, I swear not to personally harm any of your family. I can do nothing to stop my father, but despite what you think I do have a mind of my own. I will have no part in the destruction of your family." Karai looked at him expectantly.

"How do I know you'll keep your word?" Leonardo challenged, eyeing the ninja with doubt.

"I wish only to see you dead, Leonardo. You have done nothing but cause trouble for my father and me. I am neutral as to what happens to your family. I will leave them alone." When Leo hesitated, she continued. "I see you are unsure how to answer. I will let you have twenty-four hours to think about it. But believe me, Leonardo, if you say no I will continue to fight for my father against your whole family." With that, Karai was gone.

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	10. Chapter 10

Leo sat alone in his room, thinking over Karai's offer. Part of him—the leader—screamed at him that it was a bad idea and that it could only lead to trouble. But another part of him—the big brother—longed to take it on the off chance that he could actually help his family. As long as Karai kept her word, his family would be safe from the woman for the rest of their lives. But Leo had come to seriously doubt her honor, and he didn't know if he could trust her.

He knew that Raph would tell him he was being an idiot and that there was no way Karai would keep her promise. And Leo was pretty much inclined to agree with that. But there was a chance, however small, that Karai would leave his family alone. And if he managed to kill her… well, they definitely wouldn't have to worry about her after that.

Leo rubbed his eyes and glanced at his clock. It was ten o'clock; just over two hours until he had to meet Karai again. And he still had no idea what he would tell her. He really needed to be focusing on defeating the Shredder and not worrying about his own personal feud with his daughter, but defeating her could be the important first step to accomplishing that goal.

But if he died…. They really needed to take on the Shredder as a team, as a family. He couldn't just leave his brothers to fight him on their own. But could he really let Karai continue to help her father try to destroy them. She was a formidable enemy; that much Leo knew from experience.

Leo grunted in frustration. "What should I do?" he whispered to himself. He decided to meditate for the next hour and see if that brought him any closer to a decision.

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It didn't work. Leo found himself sneaking out of the lair, unsure of what he would say to the woman when he saw her. He still didn't know the conditions she had in mind; perhaps he should demand to hear them before he made his final decision.

Karai arrived right on time, as before, and greeted him quickly. "And what is your decision, Leonardo?" she demanded.

He crossed his arms and glared at her. "You haven't told me everything I need to know yet. You've explained the possible outcomes, but what of the conditions of the battle?"

"I see," she said. "That is a fair question. We will each bring one person to be our second. There will be no other spectators, and any interference on either part will not be tolerated. There is to be no dishonorable conduct; I think we can both be trusted to behave according to the rules of ninjitsu."

Leo rolled his eyes. "If you honestly think I still trust you after everything you've done, you're crazier than the Shredder." He frowned, his eyes becoming hard. "You know what? Take your 'oh-so-generous' offer and shove it! I'll take my chances against you _and _your father, with my brothers. I have absolutely no reason to face you in a duel that I know is just going to be a trap. So forget it." He turned to leave, crouching to leap onto a nearby rooftop.

"I urge you to reconsider, Leonardo," Karai said, her voice low and dangerous. "The consequences will be dire if you refuse."

Leonardo didn't turn around as he muttered, "Bring it," and left.


	11. Chapter 11

I made a change in the previous chapter, so make sure you check it out. It won't change the rest of the story but this chapter will seem confusing if you don't read the new version of chapter 10. Thanks for sticking with me!

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Leonardo tossed and turned all night, wondering if he had made the right decision. He slept little and woke with a bad headache, barely managing to focus during morning training. It was all he could do to sit still through meditation, and the concerned frowns from his father and Donatello didn't escape his notice. He evaded their questions and slipped out of the dojo as soon as they were dismissed, hoping to take a nap.

He still couldn't sleep, however, and ended up performing sub-par katas in the dojo for hours. When the pounding in his temples became too distracting he finally left the dojo and sat on the couch, closing his eyes and trying to block out his uncertain thoughts.

At dark Donatello emerged from his lab and glanced over, frowning again. "Hey, you okay?"

Leo nodded, smiling. "Yeah, I'm good. I just didn't sleep well last night."

Don nodded, although the suspicious look didn't leave his face. "I need to head to the dump to find a new part for my computer. You wanna come?"

It had become a habit for them, almost a sort of tradition. Don always wanted company when he went to the dump, and he had always asked one of his brothers to accompany him. Raphael had always hated it; he would much rather be working on his bike or out fighting Purple Dragons. Michelangelo had enjoyed it for a while, but he always became bored sitting around watching Donatello dig through heap after heap of garbage. Eventually, only Leo would agree to go with him, and Don had stopped asking anyone else. Leonardo liked keeping an eye on his brother during his excursions; as well as Donatello was trained he never seemed to remember to pay attention to his surroundings while he hunted for his "treasures." The two would talk for hours—about training, about their brothers' antics, about Don's latest research or invention—while Don searched and Leo watched for danger. They always went together; it was their time away from the insanity that filled the lair.

Despite this fact, Leo seriously considered saying no. He felt terrible, and he really didn't think he would be able to be very vigilant. However, as jumpy and nervous as he was feeling about the Shredder's latest attacks, he couldn't let his brother go out alone. So he agreed, albeit reluctantly, and the two brothers headed out.

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They had been at the dump for nearly an hour, and Don was absentmindedly rattling on about something he needed to find. Leo was trying hard to pay attention, but the noise of the shifting garbage was only making his headache worse and he found it difficult to process the words his brother was speaking. He shook his head, causing pain to spike between his eyes, and dropped his head onto his knee.

It took him longer than it should have to realize that Don was suddenly right in front of him, frowning worriedly and holding tightly to his shoulder. "I knew something was wrong," Don said accusingly, looking closely at his face. "What's up?"

"It's nothing," Leo tried to lie, but at a pointed glare from his brother he sighed. "I just have a lot on my mind…." The pain spiked again. "And I have the mother of all headaches," he mumbled, rubbing his forehead.

"You should have said something," Don admonished, standing up and pulling Leo with him. "I wouldn't have asked you to come out here if I'd known you felt bad. Let's go home." The two brothers turned to head back to the lair, and Don stopped to pick up his duffel bag. "You need to get some sleep, and in the morn—" Don stopped speaking suddenly, and Leo turned to face him.

"What…?" His eyes widened as Donatello pitched forward, collapsing to the ground and remaining still. Leonardo was at his side in a flash, heart pounding wildly out of control. He froze when he saw a small dart imbedded in his brother's neck.

"I told you there would be consequences for your refusal."

Leo whirled around, leaping to his feet and taking a defensive stance over his brother. "Karai," he growled, glaring at the woman. "What did you do to him?"

"Relax, Leonardo. It is a mild sedative and will wear off in a few hours. I merely wanted to send a message. I know of your brothers' habits. I have watched Donatello's trips to the dump, and Raphael's midnight excursions, and Michelangelo's pizza runs. I could kill them at any time if I so desired. I am being merciful in my offer, Leonardo. If you refuse, your brothers _will _die. And then you will die."

"Why not kill us if it would be so easy?"

"I do not wish to murder any of you in cold blood. I desire honorable combat with you, Leonardo, my enemy," the woman said.

Leonardo hesitated, glancing back at Don's still figure. "I will agree on one condition."

"And that is…?"

"If things seem to be coming to an end and one of us is nearing death, a short respite can be called to allow time to speak with our second," Leo replied.

Karai hesitated for a moment. "Very well. We will allow three minutes for such conversation. Then, we will end the battle."

Leo nodded shortly. "Then I accept the terms of your challenge. When will the duel take place?"

"One week from tonight, at midnight. We will meet and do battle in the warehouse. This will give us both time to prepare for our possible deaths."

Leo didn't respond, and Karai took it as he intended it—as his agreement. The woman disappeared again into the night, and Leo returned home, carrying his unconscious brother over his shoulders. "I'm sorry, Donny. I'm so, so sorry."


End file.
